Expandable shaft

ABSTRACT

The present invention relates to an expandable shaft ( 1 ) for insertion into a core, the expandable shaft have a longitudinal extension and comprising:
         a profile ( 4 ), which extends in the longitudinal direction of the shaft, the profile comprising a plurality of longitudinal grooves;   inflatable and expandable chambers which are adapted to be arranged in the grooves;   gripping means ( 3 ) which are arranged in connection to the expandable chambers, the gripping means being adapted to radial movement between a first position and a second position in view of an expansion of the inflatable and expandable chambers so that the gripping means ( 3 ) are movable in a radial direction between a first position and a second position depending on an expansion of the expandable chambers wherein   an outer cylindrical tube is arranged outside the profile ( 4 ), the outer cylindrical tube comprising a plurality of openings, and wherein the gripping means ( 3 ) are aligned with the openings of the tube so that the gripping means can project through and beyond the tube in a radial direction of the shaft during the expansion of the expandable chambers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/DK2009/000223 filed on Oct. 23, 2009 and Danish Patent Application No. PA 2009 00083 filed Jan. 20, 2009.

FIELD OF THE INVENTION

The present invention relates to an expandable shaft for rotatably supporting tubular cores of rolls of material which have to be supported during winding or unwinding processes. The material could be paper but could also be other types of web material such as textiles, metal, plastic films, foils, tapes etc. The expandable shaft for insertion into a core is of the type having a longitudinal extension and comprising a profile, which extends in the longitudinal direction of the shaft, the profile comprises a plurality of longitudinal grooves, inflatable and expandable chambers which are adapted to be arranged in the grooves and gripping means which are arranged in connection to the inflatable and expandable chambers, the gripping means being adapted to radial movement between a first position and a second position in view of an expansion of the inflatable and expandable chambers.

Furthermore the invention relates to a method of expanding an expandable shaft.

The gripping means are a type of locking-release means which can be pushed into contact with the inside of a core of a roll to be winding in such a way that the core is maintained in the same position on the shaft during the winding process. The gripping means are holding the core in position by pressing the gripping means on or into the inside of the core.

BACKGROUND OF THE INVENTION

Expandable shafts for rotatably supporting heavy large-dimension rolls are well known. Expanding of the shafts is usually done with pure mechanical forces or with fluid pressure which most often is pneumatic, since air under pressure is normally available in manufacturing plants. The shaft according to the invention is of the fluid pressure type.

U.S. Pat. No. 3,053,467 discloses one type of fluid pressure expandable shafts, where the shaft has a hollow shaft with an outer cylindrical shell comprising multiple radial openings forming a symmetrical pattern there over, a series of individual T-sectioned gripping members lying in the respective openings, an inflatable chamber in the form of a centrally placed elongated annular chamber being in connection with the gripping member. When the annular chamber inflates the gripping members are deformed outwardly and into engagement with a core. This type is also known from patent application U.S. Pat. No. 4,461,430, DE-A1-195 24 489 and DE-U1-295 10 88 3.

The above-described expandable shaft suffers from the disadvantages that all the gripping members are individually in connection with the surface of the annular inflated chamber. If the gripping elements do not have equal stiffness in all radial directions, it will lead to wobble during winding. The wobble during winding result in a winding where the edges of the rewinded material will not be exactly perpendicular to the axis of the core and furthermore the wobbling produces imbalance in the mechanical parts and causes wear down of the shaft, bearings and connected parts. The wobbling during winding can also result in poor or useless products. For example, if the shaft is used in printing works the wobbling can result in bad prints. The annular inflated chamber is liable to be damaged, and is often burst. When the air is discharged from the inflatable chamber the latter is deformed, as a result of which the gripping member may drop in the hollow shaft. In such a case, because of the internal structure of the shaft it is difficult to repair the shaft at the working site and the shaft has to be returned to the manufacturer.

Furthermore this type has the problem that great external forces are applied to the annular inflatable chamber and the chamber may be moved laterally. The annular inflatable chamber with only one air bag further tends to expand the core into an out-of round condition, and grind off material from the inner side of the core.

Another type of expanding shaft is the profile type where the shaft has a polygonal form and the surface of the shaft is provided with angularly equidistant longitudinal recesses of quadrangular shape, carrying one or more air chambers which on expanding cause pins to move radially and lock the shaft against the core of the roll, these pins being positioned on the air chambers. This type of shaft is known from, for instance, U.S. Pat. No. 5,681,007 and DE-A-44 39 035.

Because of their polygonal form and the recesses, this type of expanding profile shaft have to be manufactured of materials of high mechanical strength and rigidity. These types of shafts are often made of extruded aluminium. Extruded aluminium profile shafts do not always have enough mechanical strength and are vulnerable to stroke and relatively expensive to produce. If the shaft needs both good centring and high strength at the same time, the shafts are often made of milled steel and are very expensive to produce. Steel shafts furthermore have a considerable weight and demand extra and more expensive handling tools during the mounting and dismounting process.

Besides, because of the outer form, these types of shafts are vulnerable to stroke in connection with replacement of the cores. Damage to the profile can result in sharp corners and consequently in puncturing of the air chamber and vulnerable end pieces.

Thus, there is a need for providing a flexible solution to the above-mentioned disadvantages.

SUMMARY OF THE INVENTION

An object of the present invention is to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an expandable shaft with increased bending strength and at the same time reduce costs and total weight.

It is also important that the core does not move axially on the shaft during winding, otherwise the edges of the rewound paper will not be exactly perpendicular to the axis of the core.

It is also an object of the present invention to provide a shaft that is simple in construction, inexpensive to manufacture, and easy to disassemble for maintenance and repair.

Still another object of the invention is to provide a shaft that has a minimum number of different parts, to reduce number and cost of spare parts.

The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention in that the expanding shaft comprising an outer cylindrical tube which is arranged outside the profile, the outer cylindrical tube comprises a plurality of openings, and the gripping means are aligned with the openings in the tube so that the gripping means can project through and beyond the tube in a radial direction of the shaft during the expansion of the expandable chambers.

Shafts comprising an outer cylindrical tubular structure increase the rigidity and strength and in particular provide maximum resistance to bending stress. With the increase of the strength from the outer cylindrical tube it will now be possible to use a cheaper and lighter profile. In total an expandable shaft comprising an outer cylindrical tube reduces the weight, the cost and increases the bending stress to which the shafts are inevitably subjected during rotation. The added strength furthermore increases the lifetime of the shaft.

A shaft having an outer cylindrical tube has furthermore the advantage that the shaft can easily be disassembled for servicing and replacement. By removing the outer cylindrical tube the profile can be serviced and leaking expandable chambers can be sealed or replaced.

According to one embodiment of the invention, the profile may have at least three longitudinal grooves. Three or more longitudinal grooves will enable the gripping means to support the core in at least three different places and thereby obtain a centring of the expandable shaft.

A preferred shaft according to the invention has a profile with three longitudinal grooves which gives the best centring of the expandable shaft.

The expandable shaft may comprise a profile with three or six longitudinal grooves, the grooves preferable being arranged with an angle of 120° or 60°, respectively, between them. When the profile comprises 6 longitudinal grooves the inflatable chamber can be inflated sequentially.

According to one embodiment the gripping means may extend in the longitudinal direction of the shaft or in a tangential direction. When gripping means extend in the tangential direction of the shaft they will provide uniform support to the core around a major part of the circumference.

In an embodiment of the invention the shaft may comprise rails arranged in the grooves between the expandable chambers and the gripping means. The rails protect the inflatable chambers and contribute to a simple construction. In a further embodiment according to the invention the gripping means may be connected to the rails.

In an embodiment according to the invention one or more elastic or spring member may be arranged in connection with the rails, the elastic or spring member being adapted to force the rails into the grooves when the chambers are deflated. The elastic or spring member can be a spring, an elastic bending, an O-ring, a rubber band or the like.

In one embodiment according to the invention the rails may have a projection for detachable fixation of the gripping means. Gripping means with a small notch may hereby be pressed against the projection whereby an attachable fixation is obtained. The gripping means and/or the projection may have further engagement in the form of further projections or notches.

The gripping means may as well be clicked or screwed or in any other suitable way be detachably fixed to the rail.

In an embodiment according to the invention the profile may be divided into a plurality of modules. In this way the profile can easily be manufactured in many different lengths.

In still a further embodiment the modules may be formed with depressions for the gripping means. Two modules can be put together and gripping means may extend partly over two modules.

In one embodiment according to the invention the profile modules may be fitted on one or more rods. The modules are hereby kept in place relative to each other by being fitted on the rods. The modules are pushed together to form a long profile. The modules are placed on the rods like pearls on a string. The holes in the modules for the accommodation of the rods may be positioned between the grooves. In addition to ensuring proper placement of the modules the rods can also provide additional strength to the shaft. This additional strength derived both from the rods own strength but also by the increased strength derived from a fixed shaft. Proper placement means that the grooves have to be placed direct below the plurality of openings in the outer cylindrical tube,

The rods may be manufactured of many different materials, but if the strength is also an important issue, the rods may preferably be manufactured of any sturdy material, for example iron, steel, aluminium or other suitable materials.

According to the invention the expandable chambers may be expanded by pneumatic, since air under pressure is normally available in manufacturing plants.

The invention also relates a method for expanding an expandable shaft. The method comprising the steps of:

-   -   placing the expandable shaft into a core,     -   connecting an inflatable medium to the shaft, and     -   expanding the expandable chamber via the inflatable medium, so         that the gripping means are moved radially outwards against an         inner surface of the core, whereby the shaft is aligned inside         the core so that the core is fixated and held.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:

FIG. 1 Illustrates schematically a perspective view of an embodiment where the gripping means extend in the longitudinal direction of the shaft and with the gripping means in the first position.

FIG. 2 Illustrates schematically the embodiment of FIG. 1 with the gripping means in the second position.

FIG. 3 Illustrates schematically a perspective view of another embodiment where the gripping means extend in a tangential direction of the shaft with the gripping means in the first position.

FIG. 4 Illustrates schematically the embodiment of FIG. 3 with the gripping means in the second position.

FIG. 5 Illustrates schematically a perspective view of the embodiment of FIG. 4 where the outer cylindrical tube has been removed.

FIG. 6 Illustrates schematically the embodiment of FIG. 3, and FIG. 6(A) is a cross sectional view along line A-A of FIG. 6, and FIG. 6 (B) is a cross sectional view along line B-B of FIG. 6.

FIG. 7 Illustrates schematically a perspective view of an embodiment where the profile is divided into a plurality of modules.

FIG. 8 Illustrates schematically a perspective view of the inflation parts.

FIG. 9 Illustrates schematically the inflation distribution part of FIG. 8, and FIG. 9(A) is a cross sectional view along line A-A of FIG. 9, and FIG. 9(B) is a perspective view of the inflation distribution part.

FIG. 10 illustrates schematically a perspective view of an embodiment where the profile is divided into a plurality of modules which are fitted on rods.

FIG. 11 Illustrates schematically an embodiment of a rail with gripping means.

All the figures are highly schematic and not necessarily to scale, and they show only parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be more concretely described with reference to its preferred embodiment shown in the accompanying figures. In those figures, reference numeral 1 designates the expandable shaft according to the invention. The expandable shaft 1 has an outer cylindrical tube 2 comprising a plurality of openings wherein gripping means 3 are aligned. The gripping means 3 can project through and beyond the tube in a radial direction of the shaft. The gripping means 3 are adapted to radial movement between a first position and a second position depending on a not disclosed inflatable chambers. In FIG. 1 the gripping means 3 are elongated in the longitudinal direction of the shaft 1 and with the gripping means 3 in the first position. During expansion of the not disclosed inflatable chambers the gripping means 3 will move from the first position to a second position beyond the outer cylindrical tube 2 as disclosed in FIG. 2. In the second position the gripping means 3 will be in contact with the inside of a core of a roll to be winding in such a way that the core is maintained in the same position on the shaft during the winding process. The gripping means 3 are holding the core in position by pressing the gripping means 3 on or into the inside of the core. On the surface the gripping means 3 can furthermore coated with an elastic material, or it can have a sticky surface, thereby securing a good grip on the interior face of the core without damaging it. In some situations it can be desirable that the gripping means 3 project into the inside of the core. In this case, the gripping means 3 can have a surface with one or more spikes. The gripping means are uniformly placed on the shaft and a uniform pressure exerted simultaneously thereon by the inflatable chambers. Hereby it will be apparent that the shaft will centre itself in the core as its overall diameter is increased by inflation of the chambers.

FIG. 3 discloses an embodiment of the invention where the gripping means 3 extend in a tangential direction of the shaft 1. The gripping means 3 are in the first position. FIG. 4 discloses the same shaft 1 as in FIG. 3, but here with the gripping means 3 in the second position.

FIG. 3 and FIG. 4 disclose the gripping means 3 without any surface. From the figures it is possible to see how the gripping means 3 can be replaced from the outside of the shaft 1 without dismounting the shaft 1.

FIG. 5 discloses an embodiment of the shaft 1 with tangential gripping means 3 where the outer cylindrical tube 2 has been removed. In this embodiment the profile 4 has three grooves (in the perspective view only one groove is visible). The gripping means 3 are connected to rails 6 and the rails 6 is placed in the grooves. Upon inflating of the expandable chambers, not visible, the rails 6 with the connected gripping means 3 will move radially in the grooves and the gripping means 3 will be pushed through and beyond the openings in the outer cylindrical tube, not shown.

When the winding process is finished the core of the roll is removed from the expanding shaft 1 by deflation of the expanding chambers 7 whereby the pressure from the gripping means 3 on the inside surface of the core will stop and the gravitational effect will push the rails 6 with the gripping means 3 into the grooves. The gripping means 3 on the ventral side will still stretch beyond the openings in the outer cylindrical tube 2, but without any pressing forces it is therefore easy to remove the roll from the shaft 1. When the shaft 1 has to be placed in a new roll to be winded, the gripping means 3 on the ventral side still stretch beyond the openings in the outer cylindrical tube 2. Even though there are no pressures on these gripping means 3, they can in some situation still complicate the replacement. One or more elastic or spring members 5 can be placed around or partly around the gripping means 3 or, as disclosed in FIG. 5, around the rails 6 will automatically also draw the gripping means 3 on the ventral side into the grooves. The elastic or spring member 5 can be made in any suitable form and material for instance a metal or plastic spring or a rubber band or elastic O-ring. When the expandable chamber is inflated, the elastic or spring means will open or stretch, and when the expandable chamber is deflated the elastic or spring means will contract and all the gripping means will be drawn into the grooves.

FIG. 6 discloses the embodiment of FIG. 5 including the outer cylindrical tube 2, FIG. 6(A) discloses the cross sectional view along line A-A of FIG. 6, and FIG. 6(B) discloses a cross sectional view along line B-B of FIG. 6. The line A-A divides the shaft 1 opposite a spring member 5, the line B-B divides the shaft throughout the gripping means 3. The cross sectional view in FIG. 6(A) discloses an embodiment, where a spring member 5 is placed partly around the profile 4 and the rails 6 to automatically draw the gripping means into the grooves when the expanding chambers 7 are deflated. The number of elastic or spring members 5 per shaft depends on the length of the shaft. The cross sectional view in FIG. 6(B) discloses the gripping means 3 drawn into the grooves also on the ventral side, because of the spring member 5 as disclosed in FIG. 6(A).

FIG. 7 discloses a perspective view of an embodiment of the invention where the outer cylindrical tube 2 is disclosed with openings in the outer cylindrical tube. The profile 4 is built up in modules and has in this embodiment six longitudinal grooves 9. The gripping means 3 are arranged to be shifted hereby the gripping means 3 are in contact with substantially the entire circumferential face of the shaft and thereby secure a good grip on the interior face of a core without deforming or damaging same. The modules can be formed with depressions 10 for the gripping means 3. The depressions 10 are formed such that two modules put together form space for a gripping means 3. The profile 4 may be formed by one single module assembled by alternating the profile modules between a reflection and a 60° rotation.

FIG. 8 discloses an embodiment where the shaft is divided in to an inflation inlet part 11, a distribution part 12 and a shaft part 13. The distribution part 12 is disclosed in FIG. 9, and FIG. 9(A) is a cross-sectional view along line A-A of FIG. 9. The distribution part 12 is furthermore disclosed in perspective view in FIG. 9(B). Air inflates the expandable chambers 7 through the inlet valve 14 and via the distribution part 12. The distribution part 12 distributes the air into the tube inlet 15. In the disclosed embodiment the air is distributed into three tube inlets 15 according to a profile with three grooves with three inflatable chambers. The inflation may be provided in one or both ends of the shafts 1. A preferred embodiment is an embodiment where the expandable chambers have the form of tube pieces and are expanded by air from one or both ends of the tube pieces. Prior art often uses a closed tube with a hole for inflation in the longitudinal side. Use of a tube piece according to the invention instead is a cheap solution without need for preparing a hole, tightening and further fittings.

FIG. 10 discloses a perspective view of an embodiment of the invention where the outer cylindrical tube 2 comprises a plurality of openings wherein gripping means can be placed. The profile 4 is disclosed built up in modules (only two modules can bee seen in FIG. 10). The modules are pushed together to form a long profile. In this embodiment the profile 4 has three longitudinal grooves 9. The modules are kept in place relative to each other using in this embodiment a total of three longitudinal rods 16. The modules are fitted on the rods 16 like pearls on a string. The three holes in the modules for the accommodation of the rods 16 are positioned between the grooves 9. In addition to ensuring proper placement of the modules the rods can also provide additional strength to the shaft. This additional strength is derived both from the rods' own strength but also from the increased strength of a fixed shaft.

FIG. 11 discloses an embodiment of a rail 6 with a projection 17. The figure discloses schematically how gripping means 3 with a small notch 18 may be pressed against the projection 17 whereby a detachable fixation is obtained. The gripping means 3 and/or the projection may have further engagement in the form of further projections or notches. The rail 6 is placed above the expandable chamber in the groove in the profile. (Not disclosed in the FIG. 11). When the profile, with the expandable chambers and the rails, has been placed in the outer cylindrical tube, the gripping means can be detachable attached to the rails by pressing the gripping means 3 onto the projections 17 on the rails 6. The gripping means may as well be screwed or in any other suitable way be detachable attached to the rails.

The outer cylindrical tube may be manufactured of any sturdy material, for example iron, steel, aluminium or other suitable materials.

The profile may be manufactured by an extrusion or casting process. A preferred material is plastic easy to process, relatively cheap and with low density.

The gripping means may be manufactured of many different materials depending on the size and type of rolls to be supported under the winding process. Examples of materials could be polymer materials like polyurethane, polyethylene or polyamide or natural rubber or the like, or a metal like aluminium.

Although the invention above has been described in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims. 

1-15. (canceled)
 16. An expandable shaft for insertion into a core, the expandable shaft having a longitudinal extension and comprising: a profile, which extends in the longitudinal direction of the shaft, the profile comprising a plurality of longitudinal grooves; inflatable and expandable chambers which are adapted to be arranged in the grooves; gripping means which are arranged in connection to chambers, the gripping means being adapted to radial movement between a first position and a second position in view of an expansion of the inflatable and expandable chambers so that the gripping means are movable in a radial direction between a first position and a second position depending on an expansion of the expandable chambers wherein an outer removable cylindrical tube is arranged outside the profile, the outer cylindrical tube comprising a plurality of openings, and wherein the gripping means are aligned with the openings of the tube so that the gripping means can project through and beyond the tube in a radial direction of the shaft during the expansion of the expandable chambers.
 17. The shaft according to claim 16, wherein the profile comprises at least three longitudinal grooves.
 18. The shaft according to claim 17, wherein the profile comprises three or six longitudinal grooves, the grooves preferably being arranged with an angle of 120° or 60°, respectively, between them.
 19. The shaft according to claim 16, wherein the gripping means extend in the longitudinal direction of the shaft.
 20. The shaft according to claim 16, wherein the gripping means extend in a tangential direction of the shaft.
 21. The shaft according to claim 16, wherein rails is arranged in the grooves between the expandable chambers and the gripping means.
 22. The shaft according to claim 21, wherein the gripping means are connected to the rails.
 23. The shaft according to claim 21, wherein one or more elastic or spring members are arranged in connection with the rails, the elastic or spring members being adapted to force the rails into the grooves when the chambers are deflated.
 24. The shaft according to claim 23, wherein the member is a spring, an elastic bending, an O-ring, a rubber band or the like.
 25. The shaft according to claim 21, wherein the rails have a projection to detachable fixation of the gripping means.
 26. The shaft according to claim 16, wherein the profile is divided into a plurality of modules.
 27. The shaft according to claim 26, wherein the gripping means extend partly over two modules.
 28. The shaft according to claim 26, wherein the modules are fitted on one or more rods to ensure proper placement of the grooves in the modules in relation to the plurality of openings in the outer cylindrical tube. 